I've never had Schlafly, but I like Weyerbacher and I think the
Shipyard Smashed Pumpkin is really good. Of these two and Southern Tier's, I think they are 3 completely different beers. The only thing they have in common is pumpkin pie spices.
As an aside on Southern Tier's Pumking, I had the opportunity to have the current year's batch and the prior years batch side by side on draft. It is amazing how it changes over the course of a year.